Furnace



Octfsj, i925. Y V. R. CHADWICK FURNACE Filed March 2v, 192s 2 Sheets-sheet-l A Figi.

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v. RQ cHADwlcK FURNACE Filed kann 27, 192:5 2 Sheets-Sheet 2 Mv J i h im,

Y surfaces, but spaced apart to provide an airf' Patented Oct. 6, 1925.

1,556,284 PATENT ori-Ica^ vEaNER nUssELL 'eHAnw'Icm or LoNDoN, ENGLANn;

EnENAcE.

Application led March 27, 1923. Serial No. 628,094.

To all whom, t may concern: v

Be it known Vthat I, VERNER RUSSELL CHADWICK, a subject of the King of England, residing at London, England, have invented certain new and useful Improvements in Furnaces, of which the following is a specification.

`This invention is for improvements in or relating to furnaces, and has for its object to provide an improved construction of the same which, whilst offering advantages for the combustionv of any kind of fuel. over types of furnace hitherto known, ris particua larly suitable for burning powdered coal, such as anthracite dust. Ithas not hitherto been' practicable to burn fuel such as this, so that ithasbeen a waste product, but by means ofv the construction hereinafter described, it is possible efectively'to utilize all such fuel.

Amongst other advantages it may be stated that in furnaces of the type in which air is delivered under forced draught by steam inj ect-ion or otherwise, it has been difficult to obtain a uniform rate of combustion over the whole grate area. overcome by the present invention, and the resulting uniform rate of combustion over the whole surface of the fire-bars effects an economy by ensuring ya more complete consumptionfof the smoke and other products of combustion; another advantage isithat the rebars as hereinafter described are individually removable or replaceable;A

{'Ihis inventionA comprises a furnace-grate for burning coal-dust and likematerialsg wherein the air for combustion is' delivered through the fuel-supporting-surface .by means of a plurality ofopenings distributed over the surface, the channels communi,

eating with said openings being inclined to the.l fuel-supporting-surface at ai ysmall,

angle; such that the fuel, even although in the form of powder, will not slide down the channels and by .blocking themfprevent the` supply of air for combustion.

According to another feature of this invention, a furnace-grate-for vburning, coaldust and like materials comprises a' plurality of transverse fire-bars arrangednear one another vto receive' the fuel v-on their upper of said bars being formed with a .plurality of channels whereof each communicates at' one end with one of said air-passages, and is This` difficulty is In order to provide Y open at its yother end to the said uppersurface of the bar at 'a point spaced away from v the edge of the bar, and means for dlrecting Other features of the invention are hereinafter described with reference to the specific constructions illustrated in the accompanying drawings, and the novel details are set forth in the claims appended to this specification.

In the accompanying drawings- Figure 1 is a broken plan view showingy two fire-bars in accordance with this in-y vention;

Figure 2 is a front elevationof Figure l; Figure 3 is a section on the line 3 3 of Figure 2;

Figu

fiedvconstruction of fire-bar;

Figure 5 is a vertical section on the line 5=5 of Figure 4; v*Figure 6 is a longitudinal section showing the application of this invention to an `internally-fired boiler;

Figure 7 is a similar view of an externally-fired boiler; and f yFigure 8 is a partial section'on the line 8,-8 of Figure 3.

Like, reference characters indicate. like partsthroughout the drawings.

` vReferring first to Figures 1, 2 and 3, each fire-bar comprises end portions 10 which are substantially rectangular, and which `en-` 80 re 4 is a'broken plan showing a modi,-l

downwardly and forwardly towards the front ofthe furnace,-or opposed to the flow of air entering the furnace, and they are so dimensioned that when the bars are assembled one behind the other, with the portions l0` abutting, a channel 12 is .provided between ltheparts 1l of the'jfire-bars, vthis channel tapering upwards, as shown in Figure 3, and terminating in a narrow slot 13, (see Figure l) in the surface which supports the fuel.

for a more widespread distribution of the air, the fire-bars are formed, according to this invention, with channels or grooves 14 extending from the air-passage aforesaid along the upper surface of the bars, as shown most clearly in Figures 1 and 3. The bottom l5 of the groove is inclined at only a small angle to the upper surface 16 of the fire-bar whereon the fuel rests, this angle being less than the angle of repose of the fuel on the grate so that the fuelv will not slide down it and choke the channel or fall through into the ash-pit. The bottom 17 of the lower part of the groove 14 is sloped at a greater angle to the surface 16 aforesaid in order to provide an adequate cross-sectional area for the admission of the air, and also to accommodate a projection 18 which is formed on an adjacent bar and which serves to divert some of the air passing up the passage 12 along the groove 14. Each fire-bar is provided with a number of these grooves 14 which are made of such a length and are spaced apart by such a distance as to ensure that the air is distributed substantially uniformly throughout the whole layer of fuel on the fire-bar r1`he air flows up these grooves in a practically straight line so that air-friction losses and eddies therein are avoided.

Another feature of construction ofthe lire-bars as above described consists in the provision in each bar of a lug 19 extending laterally from the portion 11 ofthe bar in such a position that it extends through a slot 2O on the adjacent fire-bar and lies near the corresponding lug 1.9 on the said adjacent fire-bar. 1n this way, an interlocking of the bars with one another is effected, so that there is no risk of a bar rising or being forced upwards by expansion when in: use.

In Figures 4 and 5 there is illustrated'a modified Jformation of fire-bars in which the portions o f the bars between the ends are of waved formation instead of being substantially rectangular, as shown in Figure 1. The'endsl 10 of these modified bars are conveniently rectangular, and the intermediate portions 21 are so shaped as to provide a waved slot 22 corresponding to the slot 18 illustrated in FigureI 1. The intermediate parts 21 of the these bars may be arranged as shown in Figure 5 substantially at rightanlgles tothe fuel-supporting-surface 23, and when this construction is used, the channels 24, which correspond to the channels 14 of the construction first described, may be arranged to extend' from both edges of abar towards the other edge thereof, and the cooperating projeetions 25 on the adjacent fire-bars are provided in the same manner to direct the air-How along the channels or grooves 2'4. Conveniently the channels 24 in' each bar extend along the surface of the bar from a convex edge of the waved slot 22,

and accordingly, the co-operating projections 25 extend from a concavely-curved edge of the slot 22, as shown most clearly in Figure 4.

In Figure 6 there is illustrated the application of this invention to an internallyfired forced-draught boiler. The furnaceflue is indicated by the reference 26, and there is provided within the furnace a plurality of trough-shaped members 27 which diminish in cross-section from the front ends 28 towards the rear ends 29. The upper open sides of these troughs are occupied by a series of fire-bars constructed as hereinbefore described, these bars being illustrated more or less diagrammatically and indicated by the reference character 30. The air for combustion is supplied under pressure in any ordinary or desired manner from the front of the furnace 81, the usual fittings and appliances being provided, such for example, as the air-moistening device 32.

Figure 7 illustrates the applicationof this invention to an externally-fired boiler. In this case the air for combustion of the fuel may be supplied by steam air-injectors 33, 34, to a plurality of trough-shaped members 35 carrying the fire-bars 36 whereon the fuel is burnt. The trough-shaped members are, as before, preferably tapered from the front end to the rear end so as to ensure a uniform distribution of aid as between the back and front of thefurnaee and the fire-bars 36 are of the type illustrated in Figures l, 2 and 3, of substantially triangular section directed downwardly and forwardly against the flow of the entering air.

This invention provides a construction of furnace which ensu-res that the air for coin-v bustion is distributed uniformly over the whole grate area', and one, moreover, in which the air is sup-plied through a very large num-ber of small channels so that the uniformity of distribution is practically independent of the' nature of the fuel which is being burnt; it is thereby' rendered possible to burn powdered noncoking fuels, such upper surfaces, which bars have their fuelbearing portions spaced apart to provide air gaps between them and are. cast each with a plurality of air-supply channels which are directed upwards along their entire length and open. upwards each iii) through an air opening at an edge of the upper surface of each bar, which channels have their upper parts situated each in one bar and open downwards into one of said air gaps, and the top portion of each said channel is sloped downwards at an angle less than the angle of repose of the fuel on the bars so that fuel will not slide down the said channels, which bars are further cast each with a plurality of projections on one side thereof arranged to extend each into saidl channel in an adjacent bar for directing the air flow along the same. I

2. A furnace-grate for burning coal-dust and other pulverized material, comprising a plurality of fire-bars arranged side-by-side near one another to receive fuel on their than the angle of repose of the fuel on the bars so that fuel will not slide down the said channels, and the next lower portion of each channelslopes downwards at a greater angle than the vangle of slope ofthe said top portion, which bars are further cast each with a plurality of projections on one side thereof arranged to extend each into a said channel in an adjacent bar for directing the air flow along the same.

3. A furnace-grate for burning coal dust and other pulverized material, comprising a plurality of lire-bars arranged side-byside near one another to receive fuel on their upper surfaces, which bars have their fuelbearing portions spaced apart to provide air gaps between them and are cast each with a plurality of air supply channels which are directed upwards along their entire length and open upwards each through an air opening at an edge of the upper surface of each bar, which channels have their upper parts situated each in one bar and open downwards into one of said air gaps, the top portion of each said channel is sloped downwards at an angle less than the angle of repose of the fuel on the bars, and the next lower portion of each channel slopes downwards at a greater angle than the angle of slope yof the top portion, which bars are further cast each with a plurality of projections on one side thereof arranged to enter into the channels in an adjacent bar at the bottom of said top portion where the change in slope ofl the channel occurs.

4. For a furnace-grate for burning coaldust and other pulverized material, a firebar formed with a Hat upper surface to receive the fuel, with spacing means to provide an air space along one edge of said upper surface, and with a plurality of channels communicating each with one of said air spaces and extending each as a transverse open groove in the said upper surface from the said edge thereof, the bottoms of which grooves slope downwards each at an angle less than the angle of repose of the` fuel on the bars, and projections extending from the opposite edge thereof to cooperate with the channels of an adjacent fire bar.

In testimony whereof If'a-fix my signature.

VERNER RUSSELL CHADWICK. 

